Superman actor Margot Kidder, who famously played journalist Lois Lane in the ’80s movies, passed away in May, and now the coroner has revealed she died by suicide.

At the time, Kidder’s representative, Camilla Fluxman Pines, said she passed away “peacefully” in her sleep at age 69.

A statement released Wednesday by Park County coroner Richard Wood said she “died as a result of a self-inflicted drug and alcohol overdose” and that no further details would be released.

Maggie McGuane, Kidder’s daughter by her ex-husband Thomas McGuane, told The Associated Press in a phone interview that she knew her mother died by suicide the moment authorities took her to Kidder’s home in Livingston, a small town near Yellowstone National Park.

WATCH BELOW: Hollywood reacts to the death of Margot Kidder

“It’s a big relief that the truth is out there,” she said. “It’s important to be open and honest so there’s not a cloud of shame in dealing with this.”

“It’s a very unique sort of grief and pain,” she continued. “Knowing how many families in this state go through this, I wish that I could reach out to each one of them.”

Kidder had been living in Montana — which has one of the highest suicide rates in the United States — for at least 25 years, along with her daughter Maggie and her grandchildren. She became a U.S. citizen in 2005.

Kidder was born in Yellowknife, N.W.T. on Oct. 17, 1948, one of five children. (Her sister, Annie Kidder, resides in Toronto and works for Canadian registered charity People for Education. A brother, Michael Kidder, lives in Vancouver.) She travelled a lot as a child because of her father’s job and spent a few years as a child in Labrador City, N.L. She went to multiple schools and eventually graduated from Toronto’s Havergal College in 1966.

She also struggled with mental illness much of her life, and it was made worse by a 1990 car accident that left her in debt and led to her using a wheelchair for almost two years.

She got a taste of showbiz when her mother took her to New York when she was 12. It was a sign for the impressionable Kidder.

“We didn’t have movies in this little mining town. When I was 12 my mom took me to New York and I saw Bye Bye Birdie, with people singing and dancing, and that was it,” she said to The Guardian in 2005. I knew I had to go far away. I was clueless, but I OK.”

She catapulted to fame for her performance as a journalist and Superman’s love interest, Lois Lane, in 1978’s Superman. She went on to star in Superman II, III and IV.

Christopher Reeve and Margot Kidder in a scene from 'Superman' in 1978.

Stanley Bielecki Movie Collection/Getty Images

Kidder became an advocate for mental health issues after speaking out about living with bipolar disorder. She had an infamous breakdown on the streets of Los Angeles in 1996.

She credited a homeless man with showing compassion for her and saving her life during her “big, public flip-out.”

“We are all … a breath away from mental illness, homelessness, all of these things we tend to so look down on,” Kidder said in 2006. “We are all one human family and we really have to take care of each other.”

She also became a political activist in recent years and was among a group of environmentalists to be arrested outside the White House in 2011 during a protest against TransCanada’s Keystone XL pipeline.

Kidder had settled in Montana to live in a “culture-free zone” away from the spotlight.

Kidder was married and divorced three times and was also famously linked to former prime minister Pierre Elliott Trudeau. She was credited with influencing Trudeau’s decision to launch a global peace initiative during his final months in office, according to the 2009 biography Just Watch Me: The Life of Pierre Elliott Trudeau 1968-2000.

Her final years were troubled by conflicts with people who were down on their luck that she took into her home. Between August 2016 and her death in May, authorities were called to her house 40 times on reports of people trespassing, theft and other disturbances, according to police logs released to the AP under a public-records request.

The calls include responses by ambulances five times in seven months, including at the time of her death.

“We’re sad,” said Annie Kidder to Global News at the time of her sister’s passing. “We and her family are all shocked, we just found out. It happened yesterday afternoon. We’re sad and surprised.”

“It is important that we recognize the toll mental illness takes — on those who struggle with it, and on their families,” she continued over the phone from BC on Thursday. “Our family hopes that everyone who struggles is able to — without any feeling of shame — seek out, and find, help.”

Kidder’s death is one of several high-profile suicides this year that include celebrity chef Anthony Bourdain and fashion designer Kate Spade.

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If you or someone you know is in crisis and needs help, resources are available. In case of an emergency, please call 911 for immediate help.